Silver halide color photographic materials generally comprise multiple silver halide emulsion layers, each of which is sensitive to one of the three primary colors, i.e., blue, green or red, respectively, wherein the respective layer develops a yellow, magenta or cyan color to reproduce a color image according to a subtractive color process. Therefore, the image quality of the reproduced color image greatly depends on the color sensitivity characteristics of each layer and the spectral absorption characteristics of the developed hue. In general, these characteristics have not completely reached the desired height of theoretical perfection because of limitations of color developability of the compounds used.
In the reproduction of colors, the developed hue of magenta couplers is particularly important, and various improved magenta couplers have been proposed. Among them, pyrazoloazole magenta couplers are especially excellent in spectral absorption characteristics of the developed hue. In an attempt to improve the developed hue of 5-pyrazolone magenta couplers, anilino type couplers having superior spectral absorption characteristics to those of ureido or acylamino type couplers were developed, as disclosed in Japanese Patent Application (OPI) Nos. 74027/74 and 111631/74 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application").
Further, pyrazoloazole magenta couplers having reduced side absorptions have been developed as described, e.g., in U.S. Pat. Nos. 3,725,067, 3,369,897, 4,500,630, 3,061,432 and 4,540,654, and Japanese Patent Application (OPI) Nos. 33552/85, 43659/85, 162548/84, 43659/85, 171956/84, 172982/85 and 33552/85, and Japanese Patent Publication No. 27411/72. The dye images obtained from these couplers have reduced undesired absorptions in the blue and red light regions, securing an advantage in color reproduction over those obtained from 5-pyrazolone magenta couplers. In addition, the images undergo little yellowing, probably because the couplers per se are less decomposable with respect to light, heat and humidity.
The inventors previously studied pyrazoloazole magenta couplers possessing the above-described advantages, and, as a result, have found that pyrazoloazole magenta couplers represented by formula (I) hereinafter described provide particularly excellent hues. However, these couplers still have a disadvantage of stain formation (color stain on unexposed areas) during development processing, though some improvement could be seen.
The stain includes yellow stain mainly due to decomposition of magenta couplers, and color stain caused by processing solution components that become incorporated into light-sensitive materials during development processing. The stain of concern in the present invention is the color stain due to remaining processing components.
As color photographic images are usually stored as records for a long period of time or put on exhibition, stain formation is a fatal defect of such recording materials. Conventionally known methods of stain prevention include incorporation of reducing agents to light-sensitive materials. Known reducing agents for this purpose include hydroquinones as disclosed in U.S. Pat. Nos. 3,935,016 and 3,960,570; chromans and coumarans as described in U.S. Pat. No. 2,360,290; phenols as described in Japanese Patent Application (OPI) No. 9449/76; amino compounds, such as aminophenols and anilines, as described in U.S. Pat. Nos. 4,463,085 and 4,483,918; and the like.
However, combinations of the couplers represented by formula (I) according to the present invention with these known reducing agents failed to sufficiently prevent stain formation with development.
Japanese Patent Application (OPI) No. 21048/85 teaches combinations of 5-pyrazolone magenta couplers and mercapto compounds, but its purpose resides in prevention of yellow stain, essentially differing from the objects of this invention hereinafter described.